Recently, as information technology has rapidly advanced, the use of mobile devices for playing digital music files or the like (e.g., an MP3 player) has become widespread because users can conveniently carry such mobile devices and listen to selected music regardless of time and place. In order to allow a user to listen to audio data, the audio data should be decoded into pulse code modulation (PCM) format data, which is a type of digital format. Then, the PCM data can transmitted to a Digital-to-Analog Converter (DAC) and then converted into analog data that can produce an audible sound. Current state-of-the-art mobile devices are capable of playing data from various sound sources (e.g., audio data added to video data, mp3 files, and sound effects according to a user event). Furthermore, there are trends associated with converging not only audio data playback but also various functions (e.g., game services and web services) into a single mobile device. Accordingly, there is a growing need to drive such various functions at low power.
In the case of a low-power audio system that may be operated with low power, if audio data is played and a user's activity is not sensed, then power blocks except for audio blocks are ‘OFF’. Reading, decoding, and rendering should be periodically performed to play audio data. In general, reading and decoding are respectively performed via a parser and a decoder and are thus subject to the parser and the decoder, whereas rendering is subject to a direct memory access (DMA) buffer. However, because the size of the DMA buffer is fixed, it typically cannot be dynamically adjusted to play audio files.